Mitosis- lecture #13 Flashcards
what is the function of cell division?
to divide one parent cell into two identical daughter cells
what is mitosis important for?
tissue repaire
what type of cell does mitosis occur in?
eukaryotes
is cell division accurate?
highly accurate and highly complex process
what happens when HIV replicates?
trainwreck
it brings its own enzyme and therefore is not accurate at replicating
HIV changes so much because the virus isnt the same from 1 day to the next
what is used instead of mitosis in prokaryotes?
binary fission
what is a genome?
total cellular DNA content
what is a plasmid?
contains non-essential genes
small circular piece of DNA
(in addition to the bacterial chromosome)
what is the formation of DNA in eukaryotes?
many linear DNA molecules
how long is the genomic DNA in humans?
2 meters organized into chromosomes (250, 000x cell diameter)
how many chromosomes do humans have? how many chromosomes do dogs have?
humans: 46
dogs: 78
dogs have more because they’re given more from mom and dad
why do dogs have more chromosomes then humans?
the increase in chromosomes doesn’t complicate the complexity of a chromosome
what do eukaryotes have to be able to do to replicate this DNA?
must be able to replicate DNA
must be able to separate into 2 equal daughter cells
what are chromosomes?
DNA and proteins in a complex called a chromosome
what do proteins do on chromosomes?
allow the maintenance of cell structure
assist with DNA function
keeps the DNA structure highly ordered
what does DNA consist of?
100s-1000s of genes
what do genes do?
specify an individuals traits
what is chromatin?
DNA + protein = chromatin
varied degrees of condensation
what are the 2 categories of human cells?
somatic cells
gametes
what are somatic cells?
body cells
how many chromosomes are in a somatic cell? where are they located?
46 chromosomes
located in the nucleus
how many pairs of somatic cells do humans have? where are they from?
23 pairs
one version from mom and one version from dad
what are gametes?
sex cells (used for reproduction)
how many chromosomes do gametes have?
23 chromosomes
what happens to the number of chromosomes of gametes after fertilization?
double (diploid)
46 chromosomes
chromosomes are long and thin when not actively undergoing division, what is this called?
chromatin
what does chromatin do in preparation for cell division?
froms a densely coiled, folded structure
its shorter and easily visible with a microscope
why does chromatin duplicate?
in order to provide enough DNA for 2 cells following division
what is the next step after duplication?
the photocopy of the original is joined together with the original
what are the photocopy and original joined together called?
sister chromatids
what are sister chromatids attached by?
centromere
during cell division what happens to sister chromatids?
they seperate
when sister chromatids are separated but still apart of the same cell what are they called?
chromatids
when the cell completely divides what are the chromatids called?
chromosomes
each cell that results from the division will be identical to what?
the parent cell
what is mitosis used for?
produce new cells
replace damaged cells
what are the 2 phases of mitosis?
division of genetic material
division of cytoplasmic contents
what is meiosis used for?
produce gametes (sperm and egg)
what kind of cells does meiosis create?
non-identical cells
(contributes to genetic variation)
how many haploid chromosomes are produced in meiosis?
23 haploid
where does meiosis occur?
gonads (testes and ovaries)
what restores the diploid number of chromosomes in meiosis?
fertilization
sperm (23) + egg (23) = 46
what are the 2 main phases of mitosis?
interphase and mitosis
what is interphase?
before cell division therefore does not involve cell division
how much % does interphase account for in the cell cycle?
90%
what is the purpose of interphase?
duplication of chromosomes
increases in cell size and number of organelles
what are the 3 phases in interphase?
G1, S, G2
what does G1 do and how long is that process?
4-6 hours
makes organelles and enzymes, the cell grows
what does S do and how long is that process?
10-12 hours
DNA gets duplicated via DNA replication
what does G2 do and how long is that process?
4-6 hours
makes sure process is going smooth
what do all three phases involve?
protein and organelle synthesis
(anabolism, therefore building)
what is mitosis?
division of chromosomes
what % does mitosis account for in the cell cycle? how long is this process?
10%
less than 1 hour to complete
is interphase catabolic or anabolic?
anabolic
what type of intense activity occurs during interphase?
intense metabolic activity
what do the chromosomes look like at the beginning of S phase?
each chromosome is single
what do the chromosomes look like at the end of S phase?
each chromosome consists of 2 sister chromatids
in what stages of interphase does the cell grow?
G1, S and G2
at what stage in interphase is the cell the largest?
G2
what are the 2 sub-phases of mitosis?
mitosis
cytokinesis (begins before termination of mitosis
what happens during mitosis?
the nucleus and all of its contents (DNA) (including duplicated chromosomes) divide
what happens during cytokinesis?
the cytoplasm and all of its contents, nuclei and organelles, divide into two
what is the end result of mitosis and cytokinesis?
two identical daughter cells
what does each daughter cell consist of?
nucleus, cytoplasm and a plasma membrane
what does each daughter cell enter into next?
enters into G1 of interphase and begins cell division
is mitosis accurate?
accurate and very organized
how often do errors occur in divisions?
once per 100,000 divisions
what type of process does mitosis use?
metabolic (includes catabolic and anabolic processes)
what is a human cell always within a phase of?
division
after the completion of mitosis daughter cells what do they do?
enter into G1 and continue to take part in normal cellular activities
what are the 6 phases of mitosis?
prophase
prometaphase
metaphase
anaphase
telophase & cytokinesis
where is the mitotic spindle formed?
forms in the cytoplasm during prophase
what does the mitotic spindle consist of?
fibres made of microtubules and associated proteins
what partially comes apart in order to provide material for the spindle to form?
cytoskeleton
get bio material from this process
how do microtubules polymerize?
by adding tubulin in order to elongate
from left to right
how do microtubules depolymerize?
removing tubulin in order to shorten
from right to left
what is the centrosome?
the site of spindle assembly
what do centrosomes consist of?
a pair of centrioles
why do plants not have centrioles?
non-essential for the cell division process
during prophase what happens to chromatin?
chromatin becomes coiled
(forms visible chromosomes)
during prophase what disappears?
nuclear membrane and nucleolus disappear
what happens to the centrosomes during prophase?
begin side by side
move to opposite poles during prophase
how do microtubules form?
they grow out from centrosomes
what symbolizes the end of pro-metaphase?
when the 2 centrosomes are at opposite poles of the cell
what are the 3 things the spindle includes?
asters, spindle microtubules and centrosomes
how do the spindle microtubules attach to sister chromatids?
kinetochore proteins
what does the attachment of kinetochore to the microtubule cause?
causes the pull of sister chromatids to each pole of the cell
what does the spindle apparatus look like in metaphase?
its fully formed and located at opposite poles of the cell
duplicated chromosomes align down the center of the cell, what is this called?
the metaphase plate
what do asters do during metaphase?
elongate and connect to the plasma membrane
what are non-kinetochore microtubules?
microtubules that dont attach to the kinetochore, they attach to another non-kinetochore microtubule thats from the opposite pole of the cell
what is the purpose of non-kinetochore microtubules?
to elongate the cell
what occurs during anaphase?
centromeres separate from one another pulling sister chromatids apart
what cleaves cohesins that hold sister chromatids together?
separase
what happens to the overlap of non-kinetochore microtubules during anaphase?
overlap decreases
what do motor proteins do in anaphase?
walk microtubules away from one another (consumes ATP)
what does walking the microtubules away from one another do to the cell?
elongates the cell by pushing spindle poles apart from one another
what helps lengthen microtubules?
the addition of tubulin
like putting a leaf in a table, table gets longer
when is anaphase complete?
when chromosome duplicates have reached opposite poles of the cell
what is telophase the reverse of?
prophase
what reforms during telophase?
nuclear membrane and the nucleolus
what do chromosomes do during telophase?
unravel forming chromatin once again
what happens to microtubules and the spindle apparatus?
microtubules depolymerize (catabolic, exergonic, disorder)
spindle apparatus disassembles
when is telophase complete?
when the identical daughter nuclei have now divided
what is cytokinesis?
the division of the cytoplasm and its contents
what is a cleavage furrow?
occurs during cytokinesis
it forms pinching the cell into two
why does cytokinesis occur at the same time as telophase?
makes the process happen faster, can multi task with telophase and cytokinesis
how does cytokinesis occur in animal cells?
via a cleavage furrow formation (shallow groove on the surface of the plasma membrane)
what occurs on the cytoplasmic side of the membrane during cytokinesis?
interaction of actin and myosin cause the forms a contractile ring to contract
how does the animal cell finally turn into two complete daughter cells?
cleavage furrow deepens until the cell pinches off into two complete daughter cells
why cant a cleavage furrow occur in plant cells?
the cell wall is firm and not flexible
what bring the cell wall material for plant cells in cytokinesis?
vesicles from the golgi carry cell wall material
what is the process of the cell wall formation in plants?
the vesicles holding cell wall material move along microtubules to the middle of the cell
all these vesicles fuse forming a cell plate
the surrounding membrane fuses with the plasma membrane
in what kind of cell is binary fission used?
prokaryotes to divide cells
what is the first step of binary fission in prokaryotes?
cell grows double the original size
the cell divides into two what?
into two identical daughter cells that are the same size as the parent cell
because the cell grows double the original size, what is the consequence of this?
chromosomes must be highly folded and coiled as a consequence
what is the process of division in binary fission?
chromosome begins at the origin of replication
newly formed chromosome moves toward one end of the cell (with the help of proteins)
original chromosome moves to opposite pole of the cell (with the help of proteins)
the cell increases in length
plasma membrane pinches inward
two identical daughter cells are created
proteins used in bacterial binary fission are related to what?
related to proteins used in mitosis
what type of cell uses mitosis?
eukaryotes
what is between binary fission and mitosis?
intermediate
